[ Shugur-Network/relay ] fix(nips): clarify NIP-YY entrypoint a tag validation (#104)

- Updated comment to clarify a tag format: ["a", "address", "relay-url (optional)"]

- tag[1] contains the address coordinate (validated)

- tag[2] contains optional relay URL hint (no validation needed)

- Validation correctly checks only the address format in tag[1]

- All 27 NIP-YY tests pass successfully

https://github.com/Shugur-Network/relay/commit/8bd615fc3d460dc03cfb9f8e6cc860a48dd6b5ce